Processing assembly for semiconductor workpiece and methods of processing same

BACKGROUND

0001In general, semiconductor devices are manufactured by fabrication processes that form electric circuits on a semiconductor substrate, such as a silicon wafer. The fabrication processes usually include various sequences of different process steps, such as deposition, planarizing, photolithography, and ion implantation. Cleaning (such as etching and rinsing) steps are carried out between the various processing steps to remove contaminants from the substrate.

0002For example, copper is commonly deposited on silicon wafers in semiconductor fabrication. It is well known, however, that copper ions act as a contaminate in semiconductor fabrication. In that regard, copper ions, will diffuse into the silicon and change the conductivity of the silicon. Moreover, copper deposition at the bevel can flake and be unstable and therefore usually requires some etching. Therefore, copper ions are preferably cleaned or etched from all surfaces of the workpiece after a copper deposition process so as to prevent contamination and/or unwanted flaking.

0003A typical copper cleaning solution for semiconductors is dilute sulfuric peroxide chemistry. This chemistry, or other cleaning solutions, may be used to clean the back side of the workpiece, around the edge (bevel), and on other specific areas on the front side.

0004In previously designed chambers, masked areas on the wafer prevented the wafer from being fully exposed to the cleaning chemistry, which resulted in contamination. In addition, chemistry collection areas in the chamber for collecting spent cleaning chemistry were not optimized to prevent chemical splash, also resulting in contamination undesirable etching, for example, etching of the front or back side surfaces during the bevel etch process. Moreover, chemistry collection was not optimized for recovery and reuse.

0005Therefore, there exists a need for a chamber designed to clean a workpiece with reduced masking and improved chemistry collection techniques to minimize splashing and optimize recovery.

SUMMARY

0006This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

0007In accordance with one embodiment of the present disclosure, a processing assembly for a semiconductor workpiece is provided. The processing assembly generally includes a rotor assembly configured for spinning a workpiece, a chemistry delivery assembly for delivering chemistry to the workpiece, and a chemistry collection assembly for collecting spent chemistry from the workpiece. The chemistry collection assembly includes a weir that is configured to spin with the rotor assembly.

0008In accordance with another embodiment of the present disclosure, a processing assembly for a semiconductor workpiece is provided. The processing assembly generally includes a rotor assembly capable of spinning a workpiece, the rotor assembly including first and second rotors. The first rotor is movable to adjust the axial spacing between a first workpiece receiving portion on the first rotor and a second workpiece receiving portion on the second rotor, and the first rotor includes a vortex cavity that creates a pressure differential for forcing the workpiece on either of the first or second workpiece receiving portions. The processing assembly further includes a chemistry delivery assembly for delivery chemistry to the workpiece, and a chemistry collection assembly for collecting spent chemistry from the workpiece.

0009In accordance with another embodiment of the present disclosure, a method for processing a semiconductor workpiece is provided. The method generally includes delivering chemistry to a workpiece in a first process step when the workpiece is on a first rotor. The method further includes transferring the workpiece from the first rotor to a second rotor, and delivering chemistry to the workpiece in a second process step when the workpiece is on the second rotor. The method further includes collecting spent chemistry from the workpiece in a spinning weir when the workpiece is on either of the first and second rotors.

DESCRIPTION OF THE DRAWINGS

0010The foregoing aspects and many of the attendant advantages of this disclosure will become more readily appreciated by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

0011<figref idref="DRAWINGS">FIG. 1</figref> is an isometric view of a processing assembly in accordance with one embodiment of the present disclosure;

0012<figref idref="DRAWINGS">FIG. 2</figref> is a cross-sectional isometric view of a portion of the processing assembly of <figref idref="DRAWINGS">FIG. 1</figref>;

0013<figref idref="DRAWINGS">FIG. 3</figref> is a partial cross-sectional exploded view of the portion of the processing assembly of <figref idref="DRAWINGS">FIG. 2</figref>;

0014<figref idref="DRAWINGS">FIG. 4</figref> is a cross-sectional view of the portion of the processing assembly shown in <figref idref="DRAWINGS">FIG. 2</figref>, wherein the rotor assembly is in a first position for receiving a workpiece;

0015<figref idref="DRAWINGS">FIG. 5</figref> is a cross-sectional view of the portion of the processing assembly shown in <figref idref="DRAWINGS">FIG. 2</figref>, wherein the rotor assembly is in a second position for processing a workpiece; and

0016<figref idref="DRAWINGS">FIG. 6</figref> is a cross-sectional view of the portion of the processing assembly shown in <figref idref="DRAWINGS">FIG. 2</figref>, wherein the rotor assembly is in a third position for processing a workpiece.

DETAILED DESCRIPTION

0017Embodiments of the present disclosure are directed to processing assemblies for processing a workpiece, such as a semiconductor wafer, and methods of processing the same. The term workpiece, wafer, or semiconductor wafer means any flat media or article, including semiconductor wafers and other substrates or wafers, glass, mask, and optical or memory media, MEMS substrates, or any other workpiece having micro-electric, micro-mechanical, or microelectro-mechanical devices.

0018A processing assembly <b>10</b> constructed in accordance with one embodiment of the present disclosure may be best understood by referring to <figref idref="DRAWINGS">FIGS. 1-4</figref>. The processing assembly <b>10</b> has an outer wall <b>20</b> defining an inner processing chamber <b>22</b>, and a positionable rotor assembly <b>24</b> for receiving, positioning, and spinning a workpiece W disposed within the processing chamber <b>22</b>. The processing assembly <b>10</b> further includes a chemistry delivery assembly <b>26</b> for delivering chemistry to the workpiece W and a chemistry collection assembly <b>28</b> for collecting and either disposing of or recycling the used chemistry.

0019Although shown and described as being directed to a cleaning or etching assembly designed for cleaning semiconductor workpieces, it should be appreciated that embodiments of the present disclosure may be applicable in other non-cleaning semiconductor fabrication applications. Spatially relative terms used herein, for example, top, front, bottom, back high, intermediate, low, up, down, upwardly, downwardly, etc., are used to simplify the description of the illustrated embodiment for the reader and are not intended to be limiting.

0020The rotor assembly <b>24</b> is configurable in a plurality of positions to achieve various processing results for a workpiece W (for example, see <figref idref="DRAWINGS">FIGS. 4-6</figref>). The workpiece W is received in the processing assembly <b>10</b> when the rotor assembly <b>24</b> is in an automation position, e.g., a first position (see <figref idref="DRAWINGS">FIG. 4</figref>). After the workpiece W has been received, the rotor assembly <b>24</b> can be moved through a series of process steps in processing positions, e.g., second and third positions, for processing the workpiece W (see <figref idref="DRAWINGS">FIGS. 5 and 6</figref>). Generally speaking, the workpiece outer edge (bevel) and top surface (front side) can be fully processed when the rotor assembly <b>24</b> is in the second position (see <figref idref="DRAWINGS">FIG. 5</figref>), and the workpiece bottom surface (back side) can be fully processed when the rotor assembly travels through both the second and third positions (see <figref idref="DRAWINGS">FIGS. 5 and 6</figref>), as described in greater detail below.

0021The rotor assembly <b>24</b> will now be described. Referring to <figref idref="DRAWINGS">FIGS. 2 and 3</figref>, the rotor assembly <b>24</b> generally includes concentric first and second rotors <b>30</b> and <b>32</b> for receiving, positioning, and spinning a workpiece W (workpiece W shown in <figref idref="DRAWINGS">FIG. 4</figref>). A driving assembly <b>34</b> rotates rotors <b>30</b> and <b>32</b> around a center shaft <b>38</b>, and an actuating assembly <b>36</b> transmits linear movement to at least a portion of the rotor assembly <b>24</b>. As can be seen in <figref idref="DRAWINGS">FIGS. 2 and 3</figref>, both the driving assembly <b>34</b> and the actuating assembly <b>36</b> are contained within a lower housing portion <b>100</b>, which is designed to protect these components from the chemistry that runs through the inner chamber <b>22</b> of the processing assembly <b>10</b> or other environmental contamination.

0022The driving assembly <b>34</b> includes a spinning motor for driving the rotor assembly <b>24</b> via a transmission assembly <b>44</b>. The transmission assembly <b>44</b> includes a first coupler <b>46</b>, and a second coupler <b>62</b>. The upper edge of the first coupler <b>46</b> is coupled to the base portion <b>70</b> of the second rotor <b>32</b> for transmitting torque to the second rotor <b>32</b>. The first coupler <b>46</b> then transmits torque to the first rotor <b>30</b> via the second coupler <b>62</b>. In the illustrated embodiment, the first coupler <b>46</b> also serves as a protective housing for the second coupler <b>62</b>.

0023The second coupler <b>62</b> is an expandable coupling device, as seen by comparing the sizing of the second coupler <b>62</b> in <figref idref="DRAWINGS">FIGS. 4-6</figref>. As a non-limiting example, the second coupler <b>62</b> may be an accordion style bellows made from a polymer material, such as a fluorocarbon polymer, polypropylene, or polyethylene. Suitable polymers may include, but are not limited to, polytetrafluoroethylene (PTFE), perfluoroalkoxy (PFA), fluorinated ethylene propylene (FEP), polyvinylidene fluoride (PVDF), ethylene chlorotrifluoroethylene (ECTFE), polychlorotrifluoroethylene (PCTFE), and ethylene tetrafluoroethylene (ETFE). In one non-limiting example, the second coupler is a PTFE bellows having a wall thickness of about 0.015 inches or greater.

0024The expandable polymer coupler <b>62</b> provides an acid proof barrier between the chemistry in the processing chamber <b>22</b> and the center shaft <b>38</b>. In that regard, the center shaft <b>38</b> is typically made from metal, may be lubricated, and may include a ball bearing component. Therefore, the shielding second coupler <b>62</b> prevents fluid or other contamination in the center shaft <b>38</b>, which if allowed to occur, may cause part failure. Because the second coupler <b>62</b> is expandable it protects the center shaft <b>38</b> as the rotor assembly <b>24</b> is actuated through its various positions (see <figref idref="DRAWINGS">FIGS. 4-6</figref>).

0025The inventors determined that the second coupler <b>62</b>, when made from a polymer material, has enough stiffness to transmit torque to the first rotor <b>30</b> from the second coupler <b>46</b>. As seen in <figref idref="DRAWINGS">FIG. 4</figref>, the second coupler <b>62</b> can also provide an inner wall defining the inner cavity <b>78</b> of the second rotor <b>32</b>.

0026The center shaft <b>38</b> moves axially, but it does not rotate. Therefore, the rotors <b>30</b> and <b>32</b> spin around the center shaft <b>38</b>. As seen in <figref idref="DRAWINGS">FIGS. 2 and 3</figref>, the center shaft <b>38</b> is a hollow shaft configured to receive other elements or instruments for processing the workpiece W. For example, as seen in the illustrated embodiment, the shaft <b>38</b> houses nozzle <b>94</b> of the chemistry delivery assembly <b>26</b> for chemistry delivery to the back side of the workpiece W, as described in greater detail below.

0027The actuating assembly <b>36</b> is coupled to the rotor assembly <b>24</b> for actuating the rotor assembly <b>24</b> to change the relative positioning of first and second workpiece receiving portions <b>40</b> and <b>42</b> of the respective first and second rotors <b>30</b> and <b>32</b>. For example, compare the positioning of the first and second workpiece receiving portions <b>40</b> and <b>42</b> in <figref idref="DRAWINGS">FIGS. 4-6</figref>.

0028The actuating assembly <b>36</b> includes an actuator <b>48</b> to raise and lower arm <b>64</b>, which is coupled to the center shaft <b>38</b>. Non-limiting examples of a suitable actuator include a pneumatic actuator and a servo-driven actuator. The center shaft <b>38</b> includes a coupling portion <b>110</b> for coupling with the first rotor <b>30</b>. Via arm <b>64</b>, actuator <b>48</b> transmits linear movement (e.g., up and down movement) to the first rotor <b>30</b>. As a non-limiting example, the actuating device may be a ball spline.

0029In the illustrated embodiment, the actuating assembly <b>36</b> is configured to transmit linear movement only to the first rotor <b>30</b>, and not to the second rotor <b>32</b>. In that regard, the first rotor <b>30</b> is coupled to the center shaft <b>38</b>, but the second rotor <b>32</b> is not coupled to the center shaft <b>38</b> and merely rotates around the center shaft <b>38</b>. However, in other embodiments of the present disclosure, the actuating assembly <b>36</b> may be configured to transmit linear movement to the second rotor <b>32</b>, or the actuating assembly <b>36</b> may be configured to independently move either or both of the first and second rotors <b>30</b> and <b>32</b> to change the axial spacing.

0030The first and second rotors <b>30</b> and <b>32</b> are designed and configured such that the rotor assembly <b>24</b> can be positioned in various orientations to change the axial spacing between the workpiece receiving portions <b>40</b> and <b>42</b> of the respective first and second rotors <b>30</b> and <b>32</b>. In the illustrated embodiment, the rotor assembly <b>24</b> is positionable in at least three orientations, as follows:

0031(1) first rotor <b>30</b> “high” relative to second rotor <b>32</b>, which is selected for receiving or transferring a workpiece W to or from the processing chamber <b>22</b> (see <figref idref="DRAWINGS">FIG. 4</figref>);

0032(2) first rotor <b>30</b> “intermediate” relative to second rotor <b>32</b>, which is selected for generally processing the outer edge or bevel of the workpiece W, the front side or top surface of the workpiece W, as well as the back side or bottom surface of the workpiece W (see <figref idref="DRAWINGS">FIG. 5</figref>); and

0033(3) first rotor <b>30</b> “low” relative to second rotor <b>32</b>, which is generally selected for generally processing the backside or bottom surface of the workpiece W (see <figref idref="DRAWINGS">FIG. 6</figref>).

0034Although the illustrated embodiment is shown and described as moving the first rotor <b>30</b> to three different positions relative to a fixed second rotor <b>32</b>, it should be appreciated that the various positions result in a change in axial spacing between the first and second workpiece receiving portions <b>40</b> and <b>42</b>. Therefore, it should be appreciated that other embodiments directed to moving the second rotor <b>32</b> relative to a fixed first rotor <b>30</b> or moving both rotors <b>30</b> and <b>32</b> independent of one another to achieve variations in axial spacing are also within the scope of the present disclosure.

0035The first rotor <b>30</b> is a chuck rotor for receiving and supporting the workpiece W. Referring to <figref idref="DRAWINGS">FIG. 3</figref>, the first rotor <b>30</b> has a base portion <b>50</b> defining a center hole <b>52</b> through which the shaft <b>38</b> is received. The shaft <b>38</b> couples to the base portion <b>50</b> via shaft coupling portion <b>110</b> and aligns with the center hole <b>52</b> of the base portion <b>50</b>. Therefore, various elements or instruments disposed within the hollow shaft <b>38</b> (such as nozzle <b>94</b> of the chemistry delivery assembly <b>26</b>) have access to the back or bottom surface of the workpiece W when it is received on the first rotor <b>30</b>. The first rotor <b>30</b> further includes an annular outer sidewall <b>54</b> along the outer perimeter of the base <b>50</b> and an annular inner sidewall <b>56</b>, wherein the sidewalls <b>54</b> and <b>56</b> define a cavity <b>58</b> adjacent the base <b>50</b> (see cavity <b>58</b> in <figref idref="DRAWINGS">FIG. 4</figref>). Along the inner surface of the outer sidewall <b>54</b>, the first rotor <b>30</b> includes a plurality of ports <b>66</b> for delivering vortex generating gas to the cavity <b>58</b>, as described in greater detail below.

0036The first rotor <b>30</b> includes the first workpiece receiving portion <b>40</b> (see <figref idref="DRAWINGS">FIG. 4</figref>). In the illustrated embodiment, the workpiece receiving portion <b>40</b> includes a plurality of standoffs <b>60</b> extending upwardly from the outer sidewall <b>54</b> for receiving and supporting the workpiece W. The standoffs <b>60</b> are configured for contacting the workpiece W on its back side. In the illustrated embodiment, the first rotor <b>30</b> includes four standoffs <b>60</b> (see <figref idref="DRAWINGS">FIG. 1</figref>); however it should be appreciated that any suitable number of standoffs <b>60</b> are within the scope of the present disclosure. The standoffs <b>60</b> serve to create spacing between the outer sidewall <b>54</b> and the workpiece W when the workpiece W is forced against the first rotor <b>30</b>. Such spacing allows for optimized chemistry delivery to the back side of the workpiece W through the shaft <b>38</b> for back side cleaning, as described in greater detail below.

0037When the first rotor <b>30</b> has received a workpiece W, two forces acting in concert keep the workpiece W on the first workpiece receiving portion <b>40</b> of the first rotor <b>30</b> and overcome any centrifugal forces (if the workpiece W is spinning) that might force the workpiece W to deviate from its center position. First, the frictional force between the workpiece W and the standoffs <b>60</b> maintain the workpiece W on the first workpiece receiving portion <b>40</b>.

0038Second, a pressure differential is also used to maintain the workpiece W in position on the first rotor <b>30</b>. In that regard, the first rotor <b>30</b> is capable of generating a vortex force in cavity <b>58</b>, i.e., creating a relatively low pressure area below the workpiece W compared to above the workpiece W to provide a force parallel to the direction of the central axis of the first rotor <b>30</b> (i.e., orthogonal to the top surface of the workpiece W) to essentially force the workpiece W against the first rotor <b>30</b>. A suitable vortex rotor is described in U.S. Patent Publication No. US 2007/0110895, published on May 17, 2007, the disclosure of which is hereby expressly incorporated by reference.

0039In the illustrated embodiment, gas flows into the vortex cavity <b>58</b> through ports <b>66</b> that are oriented tangentially along the perimeter of the cavity <b>58</b>. The jets of gas that flow from the ports <b>66</b> create a circular path, like a tornado, generating a negative pressure region at the center of the vortex. The negative pressure of the vortex creates a pressure differential between the atmosphere and the cavity <b>58</b> to essentially force the workpiece W against the first rotor <b>30</b>. As will be described in greater detail below, the vortex is a proximate vortex designed to create a pressure differential that maintains the positioning of the workpiece W at variable distances relative to the cavity <b>58</b> of the first rotor <b>30</b> (for example, at the various positions shown in <figref idref="DRAWINGS">FIGS. 4-6</figref>).

0040Typically, nitrogen is used as a vortex gas because it is an inert gas that not only lowers the risk of contamination in the processing assembly, but also eliminates oxygen to reduce the explosion potential in the chamber. However, it should be appreciated that other inert gases, such as helium, are also within the scope of the present disclosure. Moreover, non-inert gases, such as air, may also be used if contamination and explosion potential risks are not of concern.

0041The second rotor <b>32</b> is a centering rotor for centering the workpiece W in the processing assembly <b>10</b>. As seen in <figref idref="DRAWINGS">FIG. 3</figref>, the second rotor <b>32</b> defines an inner cavity that is the inner chamber <b>22</b> of the processing assembly <b>10</b>. In that regard, the outer wall <b>20</b> of the second rotor <b>32</b> (which is the outer wall <b>20</b> of the processing chamber <b>22</b>) includes a vertical portion and a rounded upper portion <b>68</b>. At the top end of the rounded portion <b>68</b> the outer wall <b>22</b> defines an annular inlet <b>76</b> (see <figref idref="DRAWINGS">FIG. 4</figref>) to the processing chamber <b>22</b> through which a workpiece W may enter for processing (see the series of <figref idref="DRAWINGS">FIGS. 4 and 5</figref>, which show, respectively, a workpiece W outside and inside the chamber <b>22</b>).

0042Confined by the outer wall <b>20</b>, the inner chamber <b>22</b> of the second rotor <b>32</b> is defined by a base portion <b>70</b> defining a center hole <b>72</b> through which the shaft <b>38</b>, second coupler <b>62</b>, and first coupler <b>46</b> are received. Like the first rotor <b>30</b>, the shaft <b>38</b> aligns with the center hole <b>72</b> such that various elements or instruments (such as nozzle <b>94</b> of the chemistry delivery assembly <b>26</b>) have access to the back or bottom surface of the workpiece W when it is received on either the first or second rotor <b>30</b> or <b>32</b>. The second rotor <b>32</b> further includes an annular sidewall <b>74</b> along the outer perimeter of the base <b>70</b>. As described above, the transmission <b>62</b> provides an inner wall for the inner chamber <b>22</b>. Therefore, the base portion <b>70</b>, sidewall <b>74</b>, and the transmission <b>62</b> define the inner chamber <b>22</b> adjacent the base <b>70</b> (see inner chamber <b>22</b> in <figref idref="DRAWINGS">FIG. 4</figref>).

0043The inner chamber <b>22</b> within the second rotor <b>32</b> is configured for receiving the first rotor <b>30</b> and a workpiece W for processing. In that regard, the first rotor <b>30</b> has an outer circumference that is smaller than the inner circumference of the annular sidewall <b>74</b> of the second rotor <b>32</b>, and therefore is designed to nest within the chamber <b>22</b> defined by the second rotor <b>32</b>. As a result of the nesting capability of the first and second rotors <b>30</b> and <b>32</b>, the first rotor <b>30</b> is able to move axially relative to the second rotor <b>32</b>, as seen in the series of positions of the rotor assembly <b>24</b> shown in <figref idref="DRAWINGS">FIGS. 4-6</figref>. The nesting capability of the first and second rotors <b>30</b> and <b>32</b> allows for compact sizing of the inner chamber <b>22</b> to accommodate both rotors <b>30</b> and <b>32</b>, resulting in processing and manufacturing efficiencies as a result of such compact sizing.

0044Extending laterally outward from the upper end of sidewall <b>74</b>, the second rotor <b>32</b> further includes a rim <b>80</b> for supporting the second workpiece receiving portion <b>42</b> (see <figref idref="DRAWINGS">FIG. 6</figref>). In the illustrated embodiment, the second workpiece receiving portion <b>42</b> includes a plurality of centering guide posts <b>82</b> and a plurality of standoffs <b>102</b> extending upwardly from the rim <b>80</b>. The guide posts <b>82</b> are oriented at a slight angle away from the central axis of the second rotor <b>32</b> and located along the rim <b>80</b> at locations that approximate the circumference of an imaginary workpiece W. The guide posts <b>82</b> are configured to receive and contact a workpiece W on the outer bevel of the workpiece W. In the illustrated embodiment, the second rotor <b>32</b> includes ten guide posts <b>82</b> and ten standoffs <b>102</b>; however, it should be appreciated that any number of guide posts and standoffs is in accordance with embodiments of the present disclosure.

0045When a workpiece W is received by the guide posts <b>82</b>, gravity forces the workpiece W downward against the angled guide posts <b>82</b>. Therefore, as the workpiece W is received by the guide posts <b>82</b>, it becomes centered between the guide posts <b>82</b>, in both axial and radial directions, and the guideposts <b>82</b> minimize any side-to-side movement. Such centering improves the concentricity of a processed workpiece W, that is, the consistency of the average bevel clean or etch width and the range for minimum and maximum widths.

0046As seen in <figref idref="DRAWINGS">FIG. 6</figref>, as the workpiece W approaches the bottom of the guide posts <b>82</b>, it is centered and set to rest on standoffs <b>102</b>. The standoff <b>102</b> allow for a spacing between the rim <b>80</b> of the second rotor <b>32</b> and the workpiece W when the workpiece W is in the third position (see <figref idref="DRAWINGS">FIG. 6</figref>), such that spent chemistry from back side cleaning can escape to the chemistry collection assembly <b>28</b>.

0047It should be appreciated that the standoffs <b>102</b> on the second rotor <b>32</b> contact the workpiece W in different locations than the standoffs <b>60</b> on the first rotor <b>30</b>. Such a guide post <b>82</b> centering mechanism is advantageous because the workpiece W always has a centered fit within the guide posts <b>82</b>. Moreover, in such a guide post <b>82</b> centering mechanism, only select portions of the bevel and back side regions of the workpiece W are contacted by, respectively, the centering guideposts <b>82</b> and the standoffs <b>102</b>, allowing for the other surfaces of the workpiece W to be subjected to processing.

0048In addition to the guide posts <b>82</b> along the outer perimeter of the second rotor <b>32</b>, a frictional force and pressure differential are also used to maintain the workpiece W in position on the second rotor <b>32</b> when the rotor assembly <b>24</b> is spinning, as described with reference to the first rotor <b>30</b>. Regarding the pressure differential, the vortex cavity <b>58</b> of the nested first rotor <b>30</b> is a proximate vortex that can also be used to force the workpiece W against the second rotor <b>32</b>. In that regard, the vortex cavity <b>58</b> is capable of holding and maintaining a workpiece W for up to about 6 inches in distance from the vortex. This can be contrasted with a standard Bernoulli chuck which does not work with changing proximity more than about 0.080 inch. Therefore, the nesting capability allows for the rotor assembly <b>24</b> to use the vortex cavity <b>58</b> of the first rotor <b>30</b> for holding a workpiece W that is received on either of the first or second receiving portions <b>40</b> or <b>42</b> of the respective first or second rotors <b>30</b> or <b>32</b>.

0049Referring to <figref idref="DRAWINGS">FIGS. 3 and 4</figref>, the rotor assembly <b>24</b> further includes a chemistry collection assembly <b>28</b> that collects spent fluids for either waste or recycle. The chemistry collection assembly <b>28</b> includes a weir <b>84</b> that is fixedly attached and configured to spin with the second rotor <b>32</b>. In that regard, the weir <b>84</b> is a chemistry receiving channel that extends radially from the rim <b>80</b> of the second rotor <b>32</b>. Weir <b>84</b> is formed by the upper portion <b>68</b> of outer wall <b>20</b> and the extension from the top surface of rim <b>80</b>. The weir <b>84</b> may be configured to be angled downwardly such that chemistry is directed radially outwardly toward wall <b>20</b> and does not pool on the rim <b>80</b> the second rotor <b>32</b>. From the weir <b>84</b>, the chemistry travels from the edge of the second rotor <b>32</b> through the drain holes <b>86</b> at the outer annular edge of the second rotor <b>32</b> near the inner surface of wall <b>20</b> (see arrows in <figref idref="DRAWINGS">FIGS. 5 and 6</figref>).

0050The draining chemistry is collected in a fixed (non-spinning) collection chamber <b>88</b> positioned below the drain holes <b>86</b>. Chemistry may be removed from the collection chamber <b>88</b> at the drains <b>104</b> into the drain valve assembly <b>106</b> (see <figref idref="DRAWINGS">FIG. 1</figref>). The chemistry collection assembly <b>28</b> further includes a swing arm dispense cup <b>108</b> for dispensing chemistry into the collection chamber <b>88</b> after flushing the swing arm assemblies <b>90</b> and <b>92</b> before starting up the processing assembly <b>10</b>.

0051Because the weir <b>84</b> is a “spinning” weir, that is, fixedly attached to the second rotor <b>32</b>, the collection assembly <b>28</b> results in enhanced chemistry collection over previous non-spinning designs. In previously designed systems having non-spinning weirs, chemistry that spins off the workpiece W as a result of centrifugal forces has radial and tangential components. The tangential component of the spin-off chemistry is the major portion of the spin-off chemistry. The tangential component hits the inner surface of the wall <b>20</b>, for example, at the rounded portion <b>68</b> and beads up on the surface. As chemistry continues to hit the beaded surface, chemistry splatters and turns into an aerosol. Such aerosol, if left to settle on surfaces both inside and outside the processing chamber <b>22</b>, will contaminate those surfaces with spent chemistry. Therefore, the aerosol must be captured by an exhaust system to prevent such contamination.

0052In accordance with embodiments of the present disclosure, the weir <b>84</b> and the outer wall <b>20</b> spin together with the rotor assembly <b>24</b>, thereby negating the tangential component of the spin-off chemistry. With a straight radial component, the inventors have found that beading on the inner surface of the chamber wall <b>20</b> is substantially reduced, if not eliminated, creating less chemistry spattering and less resultant aerosol, both inside and outside the processing chamber <b>22</b>. A reduction in aerosol results in a reduced need for exhaust systems both inside and outside the processing chamber <b>22</b>. In addition, by eliminating beading on the inner surface of the chamber wall <b>20</b>, centrifugal force acts on the collected fluid to cause the fluid to flow toward drain holes <b>86</b>, thereby limiting the volume of fluid that collects on the collection surface of weir <b>84</b>.

0053In addition to the reduction of chemistry spattering, the “spinning” weir has the added advantage of being cleanable after each processing step. Because the weir spins, it can readily be rinsed during processing to accommodate different chemistries. As a non-limiting example, the “spinning” weir allows for the collection of an etching chemistry for recovery and recycle immediately after collecting a rinsing chemistry without contaminating the etching chemistry. In a “non-spinning” weir assembly, for example, the weir assembly described in co-pending U.S. patent application Ser. No. 12/960,372, filed on Dec. 3, 2010, the disclosure of which is hereby expressly incorporated by reference, the weirs cannot be easily cleaned, and therefore, require a plurality of weirs in a weir assembly in order to collect chemistry for recycle.

0054In the illustrated embodiment, the collection chamber <b>88</b> is not configured to spin with the second rotor <b>32</b>, and therefore there is some resultant spattering and aerosol formed in the collection chamber <b>88</b>. However, because the collection chamber <b>88</b> is removed from the processing chamber <b>22</b>, the spattering does not affect the condition of the workpiece.

0055A chemistry delivery assembly <b>26</b> delivers fluids to various locations on the workpiece, including the front side, the bevel, and the back side. The chemistry delivery assembly <b>26</b> includes a front side delivery system, which may include one or more delivery swing arms <b>90</b> and <b>92</b> (see <figref idref="DRAWINGS">FIG. 1</figref>). For example, the workpiece outer edge (bevel) may be processed using, for example, a short swing arm assembly <b>90</b> of the chemistry delivery assembly <b>26</b>. The workpiece top surface (front side) may be processed using, for example, a long swing arm assembly <b>92</b> of the chemistry delivery assembly <b>26</b>. The chemistry delivery assembly <b>26</b> further includes a back side delivery system. In the illustrated embodiment, the back side delivery system is a back side delivery nozzle <b>94</b> located in the shaft <b>38</b> for delivering chemistry to the back side of the workpiece W.

0056As mentioned above, the rotor assembly <b>24</b> is configurable in a plurality of positions, i.e., first (<figref idref="DRAWINGS">FIG. 4</figref>), second (<figref idref="DRAWINGS">FIG. 5</figref>), and third (<figref idref="DRAWINGS">FIG. 6</figref>) positions, to achieve various processing results for the workpiece. An exemplary operational sequence for the processing assembly <b>10</b> will now be described, wherein the workpiece W transitions from the first position to the third position, then to the second position, then back to the third position, then back to the first position.

0057The first step of the exemplary operational process is a workpiece automation step for placing a workpiece W in the processing assembly <b>10</b>. Referring to <figref idref="DRAWINGS">FIG. 4</figref>, the workpiece W is received in the processing assembly <b>10</b> when the rotor assembly <b>24</b> is in a first position. Specifically, the first rotor <b>30</b> is positioned in the first (or “high”) position relative to second rotor <b>32</b>, which is selected for receiving or transferring a workpiece W. In the first position, the first workpiece receiving portion <b>40</b> of the first rotor <b>30</b> is located above the processing chamber <b>22</b> such that a new workpiece W can be automatically placed on the first workpiece receiving portion <b>40</b>, or if a workpiece W has been processed, the workpiece W can be removed from the first workpiece receiving portion <b>40</b>. When received in the first position, the contact points between the rotor assembly <b>24</b> and the workpiece W are the standoffs <b>60</b> of the first rotor <b>30</b> that contact the back side or bottom surface of the workpiece W.

0058Workpiece transferring to and from the processing assembly <b>10</b> may be achieved by using an automated transfer arm or paddle (not shown). Workpiece detect sensors <b>98</b>, as seen in <figref idref="DRAWINGS">FIG. 1</figref>, are positioned to detect a workpiece W and enable automatic workpiece transfer processes. After the workpiece W has been received in the processing assembly <b>10</b>, the rotor assembly <b>24</b> can be moved to a next position for processing (e.g., either of the second and third positions, as seen <figref idref="DRAWINGS">FIGS. 5 and 6</figref>). Such movement is achieved by manipulating the actuating assembly <b>36</b> to raise and lower the position of the first rotor <b>30</b> relative to the fixed position of the second rotor <b>32</b>.

0059Although the illustrated embodiment shows a separate automation step (see <figref idref="DRAWINGS">FIG. 4</figref>), it should be appreciated that in other embodiments the workpiece W may be deposited in the processing assembly <b>10</b> in either of the second or third positions described below (see respective <figref idref="DRAWINGS">FIGS. 5 and 6</figref>).

0060The second step of the exemplary operational process is a centering and preliminary processing step. In that regard, a vortex force is generated in the cavity <b>58</b> of the first rotor <b>30</b> to force the workpiece W to the contact surfaces on the first rotor <b>30</b>, then the workpiece W is moved from the first position (see <figref idref="DRAWINGS">FIG. 4</figref>) to the third position (see <figref idref="DRAWINGS">FIG. 6</figref>). When in the third position (see <figref idref="DRAWINGS">FIG. 6</figref>), the first rotor <b>30</b> is positioned in a “low” position relative to second rotor <b>32</b>, which is selected for processing (e.g., cleaning or etching) the bottom surface (back side). When transitioning from the first position (<figref idref="DRAWINGS">FIG. 4</figref>) to the third position (<figref idref="DRAWINGS">FIG. 6</figref>), the first rotor <b>30</b> nests within the chamber <b>22</b> of the second rotor <b>32</b>. In this transition, a workpiece W is transferred from the standoffs <b>60</b> on the first rotor <b>30</b> to the guide posts <b>82</b>, then standoffs <b>102</b> on the second rotor <b>32</b> such that the workpiece W is centered by the guide posts <b>82</b>, then positioned on the standoffs <b>102</b>.

0061After being centered by the guide posts <b>82</b>, the workpiece W comes to rest on standoffs <b>102</b> on the second rotor <b>32</b> and is contained in the processing chamber <b>22</b> for processing (e.g., cleaning or etching). When positioned in the third position, the contact points between the second rotor <b>32</b> and the workpiece W are the guide posts <b>82</b> on the outer bevel and the standoffs <b>102</b> on the back side or bottom surface of the workpiece W. The workpiece W is no longer contacting the first rotor <b>30</b> or the first rotor standoffs <b>60</b>.

0062In the third position, the workpiece W may be processed (e.g., cleaned or etched). In that regard, the workpiece W is set to spin using the driving assembly <b>34</b>. The workpiece W back side then may be processed using, for example, the back side delivery nozzle <b>94</b> of the chemistry delivery assembly <b>26</b>. Because there are masked contact areas on the back side of the workpiece W when it is positioned on the standoffs <b>102</b>, this surface cannot be fully processed (e.g., cleaned or etched). Spent cleaning chemistry is collected in the chemistry collection assembly <b>28</b>.

0063The third step of the exemplary operational process is a next processing step for the workpiece W. In that regard, the vortex force is maintained, and the rotor assembly <b>24</b> continues to spin as the workpiece W is moved from the third position (see <figref idref="DRAWINGS">FIG. 6</figref>) to the second position (see <figref idref="DRAWINGS">FIG. 5</figref>). When transitioning from the third position (<figref idref="DRAWINGS">FIG. 6</figref>) to the second position (<figref idref="DRAWINGS">FIG. 5</figref>), the first rotor <b>30</b> unnests from the second rotor <b>32</b>. In this transition, the workpiece W is transferred from the standoffs <b>102</b> on the second rotor <b>32</b> to the standoffs <b>60</b> on the first rotor <b>30</b>.

0064When in the second position (see <figref idref="DRAWINGS">FIG. 5</figref>), the first rotor <b>30</b> is positioned in an “intermediate” position relative to second rotor <b>32</b>, which is selected for processing (e.g., cleaning or etching) the outer edge (bevel) and top surface (front side), as well as the bottom surface (back side). In the second position, the standoffs <b>60</b> of the first rotor <b>30</b> are located within the processing chamber <b>22</b> but above the standoffs <b>102</b> and centering guideposts <b>82</b> of the second rotor <b>32</b>.

0065In the second position, the workpiece outer edge (bevel) may be processed using, for example, a short swing arm assembly <b>90</b> of the chemistry delivery assembly <b>26</b>. The workpiece top surface (front side) may be processed using, for example, a long swing arm assembly <b>92</b> of the chemistry delivery assembly <b>26</b>. Because there are no contacts on the bevel or the front side of the workpiece W when it is positioned on the standoffs <b>60</b>, these surfaces can be fully processed (e.g., cleaned or etched). The back side of the workpiece W is also processed, to clean the areas that were masked when the workpiece W was positioned in the third position. In that regard, the standoffs <b>60</b> of the first rotor <b>30</b> contact the workpiece W in different areas than the standoffs <b>102</b> of the second rotor <b>32</b>, so that the previously masked areas may be cleaned. Similar to the process when the rotor assembly <b>24</b> is in the second position, spent cleaning chemistry is collected in the chemistry collection assembly <b>28</b>.

0066By processing or cleaning the workpiece W in both the second and third positions, all surfaces of the workpiece W are cleaned to prevent contamination of the workpiece W as a result of insufficient cleaning. In previously designed processing assemblies, unetched and uncleaned areas (i.e., masked areas) were left on the workpiece surface under the contacts required for holding the workpiece. As a result of the positionable rotor assembly <b>24</b> described herein, cleaning (including rinsing) is performed on all workpiece contact surfaces, including both back side and bevel contact points.

0067The fourth step of the exemplary operational process is a next processing step for the workpiece W. After being processed in both the third and second positions, the workpiece is returned to the third position for a final rinse and dry.

0068The fifth step of the exemplary operational process is a return to the first position for automation removal of the workpiece W from the processing assembly <b>10</b>.

0069While illustrative embodiments have been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the disclosure.